Louver grease filter

ABSTRACT

A filter for removing airborne grease has spaced front and rear walls each with a series of transverse louvers extending into the interior of the filter and opening downwardly. A filter media of expanded metal sheets is sandwiched between the front and rear walls.

BACKGROUND OF THE INVENTION

This invention relates to grease filters, and more particularly to afilter which removes airborne grease particles.

A considerable hazard is created by airborne grease particles exiting anexhaust stack. The airborne grease particles are created in abundancefrom restaurant cooking equipment. If not removed from the air, thegrease will collect on the sides of exhaust ducts and the exhaust stack.If this happens a flare up on a grill, range, fryer or other cookingequipment can touch off a serious fire in the grease in the ductwork andstack. Airborne grease in the ductwork can also settle on theventilating fans and motors for such fans resulting in a reduction inefficiency of the ventilating equipment.

Grease filters are employed at the entrance to the ductwork to alleviatethe potential hazards. The filters provide surfaces on which theairborne grease particles will collect and the collected grease willdrain away. The air entering the ductwork thereby has at least the heavygreases removed from it. One form of grease filter now in use consistsof a series of layers of an expanded metal media some of which arecorrugated. The air is forced to follow a tortuous path and in so doingthe suspended grease particles attach themselves to the surfaces oflayers of expanded metal. Such form of grease filter does an effectivejob of removing grease particles from the air but does less well inretarding a flame from shooting through the filter from the grill below.Another form of filter in use is fabricated from two layers ofsemicircular cylindrical baffles which are arranged in alternatedirections so that the air does not have a direct path through thefilter. This baffle filter has the semicircular cylindrical bafflesarranged vertically and the grease which collects on their surfacesdrains down to the bottom of the filter where it exists through drainholes and is collected in a trough for removal. This latter form offilter is particularly useful for preventing a flame from passing beyonda certain point into the ductwork beyond the filter. Because its surfacearea is limited, it functions less well to remove the airborne grease.

Any such grease filter must present a relatively low static pressureacross its thickness so as to minimize the size of the blowers needed toevacuate the ductwork and therefore to minimize the energy consumed.Such filters should also be cleanable so that they can be reused.

By my invention I provide a simple and relatively inexpensive greasefilter which functions to effectively remove the airborne grease andalso to retard flames from shooting through the filter.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a grease filterhaving spaced front and back louvered walls with filter media disposedbetween the front and back walls, the louvers of the two walls beingoffset from each other along the axis of air movement so as to force theair to travel a tortuous path.

Further in accordance with the invention, such a grease filter has thefilter media formed from sheets of expanded metal including a flat sheetadjacent the front wall and a serpentine sheet between the flat sheetand the rear wall.

It is a principal object of the invention to provide an effective butrelatively inexpensive grease filter which traps airborne greaseparticles and prevents flamethrough.

It is another object of the invention to provide such a filter which notonly traps but drains the trapped grease particles for collection in atrough.

The foregoing and other objects of the invention will appear in thedetailed description which follows. In the description reference is madeto the drawings which illustrate a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in perspective showing a filter in accordance with thisinvention installed in an exhaust hood;

FIG. 2 is a front view in elevation of the filter in accordance with theinvention;

FIG. 3 is a view in horizontal cross-section taken in a plane of line3--3 of FIG. 2;

FIG. 4 is a view in vertical cross-section taken in a plane of the line4--4 of FIG. 2; and

FIG. 5 is a partial view in vertical cross-section similar to FIG. 4 butto an enlarged scale and showing the filter in a functioning attitude.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, the grease filter designated generally by thereference numeral 10 is typically mounted at an inclined angle to thevertical, such as 45°, in a framework 11 at the entrance to an exhausthood 12 of an exhaust system. The filter 10 would be mounted in aposition above a grill or other cooking equipment in a kitchen. A trough13 is mounted along the lowest edge of the air filter 10 to collect thegrease which is trapped on the air filter 10.

The filter 10 is generally rectangular in configuration and has spacedfront and rear walls 15 and 16, respectively. The front wall 15 has topand bottom and lateral side portions 20, 21, 22, and 23, respectively,formed integral with it and projecting rearwardly from the front face 24of the front wall 15. The rear wall 16 has short lateral sections (e.g.bottom section 26) at its peripheral edges projecting forward from therear face 27 of the rear wall 16 and seated inside of the side portions20 through 23 of the front section. The side portions 20 through 23 arejoined to the lateral sections as by rivets 28.

The front wall 15 has two side-by-side series of transverse louvers 30which project inwardly to the interior of the filter 10 from the planeof the front face 24. The louvers 30 open downwardly into the interioras viewed from the front of the filter 10. The rear wall 16 is providedwith a similar pair of series of louvers 31 which also project inwardlyfrom the plane of the rear face 27. The louvers 31 in the rear wall 16also open downwardly into the interior of the filter 10.

Filter media is disposed within the space between the front and rearwalls 15 and 16, respectively. The filter media takes the form of twosheets of expanded metal. A first sheet 32 is generally flat and ismounted immediately inside the inner surfaces of the louvers in thefront wall 15. A second expanded metal sheet 33 is formed into agenerally serpentine shape and it is sandwiched between the flat sheet32 and the inner surfaces of the louvers of the rear wall 16. The axesof the folds which define the peaks and valleys of the second expandedmetal sheet 33 extend in a vertical direction within the filter 10.Drain holes 34 are provided along the lower front and rear edges of thebottom of the filter. The drain holes identify the bottom of the filter.

In operation, air is drawn by a blower (not shown) within the ductworkthrough the filter 10 and it first encounters the front wall 15 andpasses through the louvers 30 therein. The path of the air will beredirected as it passes through the front wall 15. The air must thenpass through the two sheets 32 and 33 of expanded metal and thence outof the louver openings 31 in the rear wall 16. As shown in FIG. 5, theair must travel through a tortuous path as it passes from the front face24 of the filter to the rear face 27. In so doing, the air encounterssurfaces of the louvers 30 and 31 and of the expanded metal filter mediawithin the filter and airborne grease particles will be deposited onthose surfaces. Since the air filter is mounted at an acute angle fromthe vertical, the grease which collects will flow downwardly towards abottom edge and out a drain hole 34. The grease will fall along the rearsurfaces of the louvers 30 in the front wall 15 and along the frontsurfaces of the louvers 31 in the rear wall 16, as shown in FIG. 5. Thedesign of the louvers in the front and rear walls 15 and 16 is such thatwith the filter installed at an angle such as 45° from the vertical thegrease trapped inside will flow within the filter and will not fall backinto the area beneath the filter, such as the food grill over which thefilter is located.

The filter in accordance with the present invention is very effective inpreventing the transmission of a flame for any distance through thefilter thereby reducing the danger that a flame from a grill or othercooking equipment beneath the filter will reach accumulated greasewithin the ductwork above the filter. Although the air is forced totravel a tortuous path through the filter, the louvers allow the blowerto draw the air uniformally through the filter. The static loss acrossthe filter is minimal.

The filter walls and sides can be constructed from sheet galvanizedsteel, stainless steel or aluminum formed into their desired shape bytypical stamping operations. The expanded metal media within the filtercan similarly be formed from galvanized steel, stainless steel oraluminum. Typically, the same material would be used for both the walls,sides and filter media.

I claim:
 1. A grease filter comprising:spaced front and rear walls eachhaving a series of transverse louvers extending inwardly into the spacebetween the walls, the series of louvers in the rear wall being offsetfrom the series of louvers in the front wall along the axis of airmovement through said filter so that air must travel an indirect paththrough said filter; and filter media disposed in the space between saidfront and rear walls.
 2. A grease filter in accordance with claim 1wherein said filter media are sheets of expanded metal sandwichedbetween said front and rear walls.
 3. A grease filter comprising:spacedfront and rear walls joined together at their perimeter so as to definea top, bottom and sides, said walls each having a series of transverselouvers extending into the space between the walls from the plane of theexterior face of each wall, the louvers of each series openingdownwardly and the series of louvers in the rear wall being offset fromthe series of louvers in the front wall along the axis of air movementthrough the filter; and filter media disposed in the space between saidfront and rear walls.
 4. A grease filter in accordance with claim 3wherein said filter media are expanded metal sheets disposed in saidspace.
 5. A grease filter in accordance with claim 4 wherein oneexpanded metal sheet is disposed adjacent the interior of said frontwall and a second expanded metal sheet is serpentine in configurationand is sandwiched between said one sheet and rear wall, the peaks andvalleys of said serpentine sheet extending from top to bottom.
 6. Agrease filter in accordance with claim 3 wherein drain holes are formedat the bottom of the filter.
 7. A filter for airborne grease particleswhich is disposed in a plane which is at an acute angle from thevertical, said filter comprising:spaced front and rear walls joinedtogether by lateral portions at the perimeter of the walls, said frontwall having a series of downwardly opening transverse louvers whichproject inwardly from the plane of the exterior front face of said frontwall into the space between said walls, said rear wall having a seriesof downwardly opening transverse louvers which project inwardly from theplane of the exterior rear face of said rear wall into the space betweensaid walls, the series of louvers of said rear wall being offset fromthe series of louvers of said front wall relative to the principal pathof air movement toward and away from said filter so that the air isforced to follow a tortuous path from said front face to said rear face,drain openings being formed in and disposed adjacent the bottom of saidwalls; and a filter media disposed within the space between said frontand rear walls.